Book excerpt: From killer toads, feral felines, and brown tree snakes to multiple invaders in the Great Lakes and Lake Victoria, Alien Invaders explores the impact on our ecosystems of the wave after wave of invaders and why they have become a worldwide concern. Environmentalists Jane Drake and Ann Love take us on a journey from the days of sailing ships and shipboard rats to the fungus that sparked the Irish potato famine to the beautiful but deadly purple loosestrife strangling native wetlands, while presenting the concepts of biodiversity and endangered species. Learn where the invaders originate, how they travel, what they displace, why the invaded natural system is vulnerable, and what can be done. Discover if you are an invader or a saver and how you can help.